1. Field of the Invention
The present invention relates to a hand-held abrasive cutter for forming grooves in a hard constructional component, comprising a cutting-off disc, a guide member for guiding the cutter along the constructional component, a hood for covering the cutting-off disc and connected with the guide member by a common rotatable axle and pivotable in a direction of the guide member against a spring-biasing force, a stop member associated with the hood or the guide member, and a plurality of locking elements provided on the hood or the guide member and arranged one after another, with the stop member being displaceable, in its release position, along the locking elements and formlockingly engaging, in its locking position, at least one of the locking elements.
2. Description of the Prior Art
European Patent EP-O 340 467 discloses an abrasive cutter with a cutting-off disc for forming grooves in hard constructional components, e.g., such as concrete and stone components. The abrasive cutter is arranged in a hood and a guide member for safety reasons and for removing dust formed during cutting a groove. The abrasive cutter, together with the cutting-off disc, are arranged on the hood, with the axis of the cutter and the disc extending horizontally. A common axle connects the hood and the guide member. The hood is pivotable, against a spring-biasing force in a direction of the guide member until the hood abuts a stop member arranged on the guide member. The stop member is displaceable, in its release position, along a plurality of locking elements provided on the guide member and arranged one after another. A spring biases the stop member into engagement with the locking elements in its locking position.
To displace the stop member from its locking position into its release position, the stop member should be lifted from its engagement with the tooth-shaped locking elements against a spring-biasing force in order to break the formlocking connection of the stop member with the guide member. With a spring that applies a small biasing force, there exists a danger of shifting of the stop member from its predetermined position as a result of inadvertent displacement of the stop member during the placement of the cutter on a constructional component or the lifting of the cutter of the constructional component. This is a serious drawback as the shifting of the stop member leads to a deviation of the groove depth from a predetermined size.
Accordingly, an object of the present invention is a hand-held abrasive cutter with which grooves with a constant depth can be formed and in which an inadvertent shifting of the stop member from a predetermined position is prevented.
This and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a locking member displaceable, in the locking position of the stop member, in the operational region of the stop member.
The locking member, which is displaced in the operational region of the stop member, prevents the stop member from displacement from its locking position to its release position, i.e., blocking of the stop member takes place. The locking member can be formed, e.g., as a shackle arranged sidewise of the stop member and displaceable, in the locking position of the stop member, immediately behind the stop member in its axial projection.
An easy displacement of the stop member along the locking elements in insured when both the stop member and the locking elements are provided on the hood.
The dimensions of the abrasive cutter can be made small when, advantageously, the stop member is displaceable along a bolt which is supported on the hood, and the locking member is also displaceable along the bolt relative to the stop member and is fixable on the bolt in the locking position of the stop member.
A simple and a cost-effective, from the manufacturing point of view, connection of the locking member with the bolt is preferably achieved when the locking member is connected with the bolt by a threaded connection.
Advantageously, a spring is provided between the locking member and the stop member. The spring biases the stop member into its locking position. In this way, the stop member is automatically displaced into its locking position as soon as its release position is broken. The force necessary for the displacement of the stop member into its release position depends on the spring force of the spring arranged between the stop member and the locking member. Because the spring is supported against the locking member, the biasing force applied to the stop member can be adjusted by adjusting the distance between the stop and locking members, i.e., the biasing force of the spring depends on this distance. E.g., at a larger distance between the locking and stop members, the spring is released to a great degree, and the stop member can be displaced to its released position by an application of a small force. At a smaller distance between the locking and stop members, the force necessary for the displacement of the stop member to its release position in much greater.
To achieve an easy movement of the spring and to be able to prevent its contamination, preferably, the spring at least partially is received in annular groove formed in the stop member and opening toward the locking member.
The hood and the guide member are connected with each other with a possibility of a pivotal movement relative to each other about a common rotable axle. In order to insure that the hood and the guide member can pivot only within each other and cannot be pivoted out of each other, the bolt advantageously is connected with a detent spring which is arranged on the hood and is formlockingly engageable with the guide member in the initial position of the hood, and is supported on the inner surface of the guide member in the operational position of the hood. The detent spring, e.g., can be arranged on the inner surface of the hood. To insure cooperation of the detent spring with the guide member, advantageously, the detent spring projects past the outer contour of the hood in the initial position of the hood, and is provided with a locking nose projecting in a recess formed in the inner surface of the guide member.
For changing the cutting-off disc, it should be readily accessible to a suitable tool. To this end, advantageously, the formlocking connection between the detent spring and the guide member is broken by displacement of the bolt. By displacing the bolt, the hood and the guide member can be displaced apart from each other by pivoting the guide member about the common axle away from the hood.
Advantageously, the guide member is provided with a window opening arranged in the circumferential regional of the cutting-off disc. The window opening permits an early detection of the wear and so-called xe2x80x9cfiringxe2x80x9d of the cutting-off disc.
Two guiding rollers are provided coaxially with the common axle of the hood and the guide member. The guiding rollers, together with a guide surface which is provided on the guide member in its region remote from the hood, insure displacement of the cutter on a surface of to-be-cut constructional component. Preferably, the guiding rollers project beyond the guiding surface by about 1 mm.
At the upper portion of the hood remote from the guide member, there is provided a suction union or connection connectable with a suction device for sucking away a grinding dust formed during cutting of the groove. One suction union can be replaced by another union in order to connect the cutter with another suction device.
At opposite sides of the hood, there are provided two connection thread for connecting a handle to the hood. The two connection threads are coaxial with each other. The longitudinal axes of the threads extend parallel to the axis of the cutting-off disc.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiment, when read with reference to the accompanying drawings.